With continuous evolution of wireless communication technologies and standards, the mobile packet service has been developed tremendously, and the data throughput capability of a single terminal is constantly increasing. Take the long-term evolution (LTE) system for example, at 20 Megabits per second (Mbps, also called M), a maximum of 100 Mbps downlink data transmission rate can be supported within the bandwidth, while in the LTE-A (LTE-Advanced) network, the data transmission rate will increase and can reach even up to 1 Gigabits per second (Gbps).
Existing LTE systems mainly comprise a core network (CN), an access network (ANs) and user equipments (UEs), and its network architecture is shown in FIG. 1. Wherein, the CN mainly comprises a Mobility Management Entity (MME) responsible for control plane (CP) information and a Serving Gateway (S-GW) for user plane (UP) data transmission. The AN in a Heterogeneous Network (HetnNet) mainly comprises a Macro evolved Node B (Macro eNB) and various types of Low power nodes (LPNs), the nodes are connected via the X2 interface, and each node separately manages its own radio resource to ensure the resource is fully and effectively used. The interface between the eNB and the MME is called S1-C interface and the interface between the eNB and the S-GW is called S1-U interface, the S1 interfaces ensure the interaction and transmission of information and data between the AN and the CN. In the aspect of radio interfaces between the AN and the UE, an existing radio connection is a one-to-one dedicated link, and the link carries Signaling Radio Bearer (SRB) and data radio bearer (DRB) exchanged between the UE and the network.
The appearance of LPN is to meet growing demand for data services and geographical inequality of the services, in the process of operators deploying next-generation communication networks (that is, the LTE network), LPNs (also known as small cells (SCs)) are continuously increased to meet the hotspots' demand for data services. However, with the increase of the SCs, the network deployment environment is becoming more complex, which brings more problems. This is because the SC coverage range is much smaller as compared to the macro cell (MC), and the number of SCs is relatively large, therefore when the UE moves within the network, the signal quality of the radio link may change rapidly, resulting in frequent inter-cell handovers, and even leading to frequent data service interruptions or call drops or other problems, which also makes the user's data throughput and call experience degrade. With the increasing number of SCs deployed by operators and individuals in the future, the abovementioned situation will become increasingly serious.